The short message system (SMS) has become a very popular approach to distribute advertising because of its largest possible range of audiences and low cost. This obviously results in a more and more serious SMS spam problem.
Spam is not new in the information technology (IT) industry. Notorious email spam has bothered Internet users for a long time. There are already some technologies that may deal with the email spam, including content filtering, white list and black list. However, one of the most important and effective methods for preventing email spam is to protect email address carefully and not reveal email address to spammers unconsciously.
The SMS spam problem is becoming more complex, because the numbers of mobile phones are more regular and continuous. SMS spammers needn't collect the numbers of mobile phones as email spammers. SMS spammers can easily obtain a large amount of mobile phone numbers by emulating each number of a predefined continuous phone number segment, which is also a very popular method for existing SMS spam systems.